ADAPTING THE MALUSIM APPLE TREE MODEL FOR THE 'GALA' CULTIVAR
The MaluSim apple tree model was first introduced by Lakso and Johnson (1990) and has since been steadily modified and improved. One of the main goals of MaluSim is to be able to predict fruit abscission and response to thinning applications, based on weather data and therefore, carbon status of the tree. MaluSim simulates seasonal carbon production and is used with sub-models: 1) leaf area development and abscission, 2) canopy photosynthesis and tree respiration, 3) carbon partitioning, and 4) fruit growth and abscission. The model is a big-leaf type for simplification and ease of use. Our specific project was aimed to parameterize the model to the difficult-to-thin cultivar Gala. The standard MaluSim model is based on data collected mostly on Empire apples. For the fitting, growth comparison for the two cultivars has been done, and the model has been adjusted according to the data obtained for Gala. The two cultivars appear to have very similar growth rates and physiology in general, but the greatest difference appears to be in the abscission process. In both cultivars, fruit abscission is induced by a reduction in fruit growth rate relative to the expected maximal growth. Gala trees, however, retain a greater percentage of fruit that have slower growth rates than Empire trees. This relationship is central to the fruit abscission prediction sub-model.
Doerflinger, F.C., Lakso, A.N. and Braun, P. (2015). ADAPTING THE MALUSIM APPLE TREE MODEL FOR THE 'GALA' CULTIVAR. Acta Hortic. 1068, 267-272
carbon partitioning, fruit abscission, fruit growth, photosynthesis, thinning, weather